Bone preserving level of osteotomy in short-stem total hip arthroplasty does not influence stress shielding dimensions – a comparing finite elements analysis

Background The main objective of every new development in total hip arthroplasty (THA) is the longest possible survival of the implant. Periprosthetic stress shielding is a scientifically proven phenomenon which leads to inadvertent bone loss. So far, many studies have analysed whether implanting different hip stem prostheses result in significant preservation of bone stock. The aim of this preclinical study was to investigate design- depended differences of the stress shielding effect after implantation of a selection of short-stem THA-prostheses that are currently available. Methods Based on computerised tomography (CT), a finite elements (FE) model was generated and a virtual THA was performed with different stem designs of the implant. Stems were chosen by osteotomy level at the femoral neck (collum, partial collum, trochanter sparing, trochanter harming). Analyses were performed with previously validated FE models to identify changes in the strain energy density (SED). Results In the trochanteric region, only the collum-type stem demonstrated a biomechanical behaviour similar to the native femur. In contrast, no difference in biomechanical behaviour was found between partial collum, trochanter harming and trochanter sparing models. All of the short stem-prostheses showed lower stress-shielding than a standard stem. Conclusion Based on the results of this study, we cannot confirm that the design of current short stem THA-implants leads to a different stress shielding effect with regard to the level of osteotomy. Somehow unexpected, we found a bone stock protection in metadiaphyseal bone by simulating a more distal approach for osteotomy. Further clinical and biomechanical research including long-term results is needed to understand the influence of short- stem THA on bone remodelling and to find the optimal stem-design for a reduction of the stress shielding effect

Kritische Erfolgsfaktoren für originäre und derivative Gründungen und KMUs

The dissertation contains the investigation of specific success factors for original and derivative ventures and SMEs. These are team diversity for new ventures in university spin-offs, incentives for SMEs, and gender in business succession in family firms. The focus is shift away from a generalized consideration of success factors to a specific one. This approach makes it possible to consider the specific context surroundings and to detect success factors that are of high importance for the organizations observed.Die Dissertation enthält die Analyse spezifischer Erfolgsfaktoren für originäre und derivative Gründungen und KMUs. Diese sind Teamdiversität für Neugründungen in University Spin-Offs, Anreize für KMUs und Gender in der Unternehmensnachfolge in Familienunternehmen. Der Fokus wird dabei von einer generalisierten Betrachtungsweise der Erfolgsfaktoren auf eine spezifische verschoben. Durch diesen Ansatz ist ein besserer Kontextbezug möglich und die Aufdeckung hochrelevanter Erfolgsfaktoren für die betrachteten Organisationen

Gender differences in blood transfusion strategy for patients with hip fractures - a retrospective analysis

Finanziert aus dem DFG-geförderten Open-Access-Publikationsfonds der Universität Siegen für ZeitschriftenartikelBackground: In the last decades, transfusion therapy with allogenic blood has progressively shifted to a more restrictive approach. The current study analyzed the transfusion practice and transfusion-associated factors in a regional trauma center over the course of five years. Methods: Retrospective analysis of all patients undergoing surgery for hip fractures in a level 1 trauma center of an academic teaching hospital from 2010 to 2014 (n=650). The number of transfused packed red blood cells (PRBCs), preoperative Hb concentrations, and intensive care unit (ICU) and hospital length of stay (LOS) were analyzed. A logistic regression analysis was performed to evaluate transfusion and ICU LOS-associated risk factors. (Ethical Review Board approval: 2015-497-f-S). Results: From 2010 to 2014 the average number of PRBCs transfused per patient decreased continuously despite similar preoperative Hb levels. During the same period, ICU LOS increased while hospital LOS decreased. Advanced patient age, preoperative Hb concentrations, surgical complications, and ICU LOS were associated with increased transfusion requirements. Although preoperative Hb levels were lower, females received fewer PRBCs compared to males. Conclusion: Over the course of five years, a restrictive transfusion strategy was implemented within clinical practice in patients undergoing surgery for hip fractures. In parallel, a significant reduction in the hospital LOS and an increased ICU LOS was noted. Whether there is an association between increased ICU LOS and decreasing hospital LOS and whether there is a gender effect on transfusion requirements in patients with surgery for hip fractures should be subject to further research